Low compression help??

R

robert3966

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May 31, 2011
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I have a Johnson 1993 150 horse model #VJ150ELATR Having issues with loosing power. Checked compression, left side 95#, 93#, 92#. Right side 97#, 102#, 100#. Does anyone think this is low compression or is this normal compression?? Thnx.
 
L

levi_tsk

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Dec 26, 2010
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907
Re: Low compression help??

define "loosing power" for us please it does_____ when you do ______

this IS a little low but its also even and probably not the problem but do a decarb as described in the top secret files and check it again and see if it comes up
 
R

robert3966

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May 31, 2011
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Re: Low compression help??

levi_tsk said:
define "loosing power" for us please it does_____ when you do ______

this IS a little low but its also even and probably not the problem but do a decarb as described in the top secret files and check it again and see if it comes up
Click to expand...

Motor was rebuilt 18 months ago. Over the winter i had all 6 carburators rebuild and all new reeds installed. (thinking preventative maintenance) This year lost 10 mph on top end and a small stumble on fast excelleration. I was told the carburators have no adjustment on them- they come factory set. Had installed 6 new float bowls. When engine bogs on fast excelleration, I push the key in to give it a little choke and problem clears up except for top end. Thx for your help and for responding.
 
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levi_tsk

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Dec 26, 2010
Messages
907
Re: Low compression help??

its HAS to be the carbs one of the gurus on here might be able to help you better though
 
M

Monte1961

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May 8, 2011
Messages
1,180
Re: Low compression help??

Pull every plug noting witch one looks like its running the leanest. Start there.
 
jbjennings

jbjennings

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Jul 18, 2007
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3,903
Re: Low compression help??

Just a thought, since it sounds like carbs to me also, but have you tried seeing what happens if you run it without the cowl? You may have an exhaust leak, or a vacuum leak. It was rebuilt 18 months ago with new rings, pistons, and such, and it has the aforementioned compression?? Just curious at the components fixed or replaced in the rebuild.
JBJ
 
JB

JB

Honorary Moderator Emeritus
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Mar 25, 2001
Messages
45,907
Re: Low compression help??

Your compression numbers are just fine. Don't worry about them.

Outboards never loose power; they might lose a bit, but that is a different thing.

When power seems to drop, what happens if you pump the primer bulb? What if you push the key in to prime it??
 
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